This invention relates generally to methods of freezing tissue and, in particular, to a method of freezing tissue samples to prevent deterioration of the cellular structure of the tissue or in preparation for immediate examination, with or without staining and fixing.
Methods of freezing tissue for cytological or histological examination are known and available. For example, freezing of tissues by cryogenic techniques using liquid nitrogen are relatively common, albeit expensive. Moreover, there may be damage to the cellular structure which interferes with a rapid and accurate examination of cryogenically frozen tissue.
A Method of Freezing Fishery Products is known from U.S. Pat. No. 4,601,909 issued to Nagoshi on July 22, 1986. This method includes the steps of preparing a brine containing rapeseed oil, propylene glycol, calcium chloride and water, cooling the brine and immersing the seafood in the cooled brine until it is frozen. This method reduces or eliminates breakdown of muscle tissue in the seafood. Hence, deterioration in quality of the frozen product is prevented or reduced.
A similar process for Quick Freezing of Meat is disclosed and claimed in U.S. Pat. No. 4,654,217 issued to the same inventor on Mar. 31, 1987. The process disclosed in this later patent is similar to that disclosed in the earlier patent except that it is applicable to beef, poultry, pork and the like.
U.S. Pat. No. 4,657,768 issued to Nagoshi on Apr. 14, 1987, discloses a Freezing Method for Perishable Foods which includes placing a perishable food in a heat conducting container and causing the other surface of the heat conducting container to contact cooled brine or a liquefied gas. Accordingly, the perishable food is frozen quickly without immersion.
U.S. Pat. No. 4,689,963 issued to Sakai on Sept. 1, 1987, relates to a Method of Freezing Foods. The method of Sakai is similar to the method of Nagoshi except that a layer of brine is placed in the heat conducting container along with the perishable food. Freezing proceeds only from the portion which is in contact with the brine and the potential for the food to stick to the container is reduced.
There is no teaching or suggestion in any of these patents that these processes can be used to freeze tissue samples for cytological or histological examination.
Accordingly, it is desirable to provide a process for freezing tissue samples for purposes of cytological or histological examination.
It is, therefore, an object of the invention to provide a process for quick freezing tissue samples for histological and cytological tissue examination.
A further object of the invention is to provide a method of freezing tissue samples which does not destroy the cellular structure of the sample.
Still another object of the invention is to provide an economical method of freezing tissue samples.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.